Mugen Power Slim Extended-Capacity Battery for Nokia Lumia 710 Mugen Power Slim Extended-Capacity Battery for Nokia Lumia 710 and Nokia 603 1,500mAh, 3.7V power rating; Lithium-ion technology Extended-capacity battery provides additional talk and standby times without adding thickness to your phone Standard-size battery fits in existing battery compartment without the need for a larger battery cover door Keeps your phone powered even with heavy phone and data usage